#include <time.h>
#include <limits.h>

clock_t clock()
{
    struct timespec ts;

    if (__clock_gettime(CLOCK_PROCESS_CPUTIME_ID, &ts))
        return -1;

    if (ts.tv_sec > LONG_MAX/1000000
     || ts.tv_nsec/1000 > LONG_MAX-1000000*ts.tv_sec)
        return -1;

    return ts.tv_sec*1000000 + ts.tv_nsec/1000;
}
